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How to Clean a Battery That Is Corroded

July 05, 2013

Car batteries are filled with sulfuric acid. Chemical reactions between the sulfuric acid and the metal of the battery posts lead to the buildup of corrosion on the car battery. Battery corrosion is typically more prevalent on the positive battery post, but buildup can occur on both the negative and positive posts over time and affect the battery’s ability to perform properly. While it is mostly safe to clean battery corrosion yourself, it can be hazardous because you are dealing with electricity and chemicals. Gloves and safety glasses are not mandatory, but their use is advised. If you follow these steps, you clean your car battery safely and easily.

Step 1: Disconnect the Battery.
The important first step in cleaning battery corrosion is to disconnect the wires from the negative battery post. If you disconnect the positive post first, you risk electric shock or burns if your tools come in contact with the exposed post and the metal of the vehicle. If the wires don’t come off easily, try twisting them back and forth while lifting up. The battery corrosion might make it difficult but they will come off with a little effort.

Step 2: Clean Corrosion from the Battery.
After disconnecting the positive battery post you can put the wires aside for later and focus on cleaning the corrosion on the battery. The best way to dissolve battery corrosion is with a cup of water mixed with a teaspoon of baking soda. Take this mixture and either slowly pour it directly on the battery corrosion or wet an old toothbrush or rag with it and use it to brush away the corrosion. The baking soda will dissolve the corrosion from the battery very effectively without requiring too much effort or making a mess. Another popular method, and readily available at any convenience store, is a can of soda. You can pour the soda over the corroded battery posts and it will clean them by dissolving the corrosion much like the baking soda mixture.

Step 3: Clean the Terminals.
After the corrosion is removed from the battery itself, take a wire brush or the toothbrush with baking soda mixture and clean the car battery terminals, paying close attention to where they connect to the battery posts to ensure a good connection now that the posts themselves are clean.

Step 4: Finish and Reconnect.
Now you are ready to finish cleaning the battery and reconnect it to the car. If you used soda, rinse it off with a little water. Next, wipe away any excess moisture on or around the battery, the posts, and terminals. Now you are ready to reconnect the battery, starting with the positive terminal and then the negative.

If you still have problems with your battery or electrical system after cleaning away battery corrosion, the ASE certified mechanics at The Tire Choice & Total Car Care can inspect your electrical system including your alternator and starter as well as the battery and battery cables. We also offer a free towing service for our customers who are stranded and unable to bring their vehicle into our shop.